If you like to play Solitaire, then you may want to have a look at FreeSolitaire by Michael McCulloch and Goodsol Development Inc. FreeSolitaire contains ten of the most popular card-games and has some really nice features that make it a more than excellent replacement for the standard MS fluff. If http://www.freesolitaire.com seems sluggish, just remember you're sharing it's bandwidth with a couple of million others...
FreeSolitaire uses PNG & MNG for its internal advertising banners.

DingoSearch performs quick searches for web pages using several of the most popular search engines available and presents the results in a compact easy to view format. Double-clicking on a result set line takes you directly to the selected page in your browser.

NetStock is a simple little stock and mutual fund internet quote retrieval program. It includes export functionality for those users that also have Quicken. Netstock uses PNG & MNG to display ad-banners.

FoopChat is a standalone system designed to allow people to socialize privately and securely. It has recently been extended with MNG animation support! If you are looking for a chat-client and server system, than FoopChat with MNG is your choice.